2017 was an unusually eventful year for lawyers who track the ascertainability requirement, which had, for the last five or so years, become a staple argument for class action defendants. Here are the top issues that class action litigators had to contend with.

Circuit split on administrative feasibility.

This year, both the Second and the Ninth Circuits have held that administrative feasibility is not required to show ascertainability. The Ninth Circuit may have gone even further: some of the language it used suggests that it may not view ascertainability a requirement at all for certifying a class. (It had stated there was “no freestanding requirement” for administrative feasibility.) Several trial courts within the Ninth Circuit have interpreted this language to mean that there is no ascertainability requirement—explicit or implicit—in the Ninth Circuit at all.

Meanwhile, the Eighth Circuit affirmed the “by reference to objective criteria” prong of the ascertainability requirment. And the Third Circuit, which still requires a showing of administrative feasibility, backed off on how stringent that standard must be.

What meets the burden of showing “objective criteria”?

Several courts have held in the last year that you can’t shift the burden to defendants to show a lack of ascertainability; the plaintiff must proffer actual evidence that the class is identifiable.

But how does a plaintiff establish that?

The Third Circuit has held that affidavits by potential class members are not presumptively infeasible; a decision that contrasts with a number of cases that had previously held that affidavits are not good evidence of ascertainability. By contrast, the Sixth Circuit held that sometimes, affidavits are not sufficient to determine class membership where the lack of other evidence is the plaintiffs’ own fault.

Fail-safe classes.

I’ve written before about how the Fifth Circuit has held that fail-safe classes (where membership in the class is defined by a merits finding in the case) are not a reason to deny certification. It appears now the Ninth Circuit may have joined them. [] In a recent memorandum opinion, it noted, but did not hold, “that our circuit’s caselaw appears to disapprove of the premise that a class can be fail-safe.”

For a number of years, Third Circuit precedent on ascertainability had driven a number of arguments, and secured a number of denials of class certification. Various appellate courts appear to be restricting the applicability of these arguments, so keep watch.